A survey of the capitellids from the Hawaiian Islands has yielded 16 species in seven genera, most represent new records and two species are newly described,
Notodasus dasybranchoides sp. nov. and
Scyphoproctus edmondsoni sp. nov. The species
Capitella minima,
Capitellethus cinctus and
Scyphoproctus pullielloides are the most common and widely distributed capitellids in Hawaii, present in subtidal sediments surrounding outfall diffusers and also at reference locations. The species
Mediomastus californiensis and
Capitella giardi may have been introduced to Oahu from different sources, the former is abundant in soft sediments of Honolulu and Pearl Harbors and the latter is found associated with commercial oysters in muddy ponds. The genera
Branchiocapitella and
Pulliella are considered herein as synonyms of
Capitella and
Scyphoproctus, respectively. This paper is the first comprehensive study of the Hawaiian capitellids and all species are described and illustrated with line drawings, color and SEM photographs. A key to all 16 capitellid species found in shallow waters from the main Hawaiian islands is provided.
